1. Field of the Disclosure
The present invention relates to a lighting control method, a lighting apparatus and a lighting system.
2. Discussion of the Related Art
In the lighting industry, studies and researches have been still under development on a lighting source, a light emission type and a driving method of a lighting apparatus.
A conventional lighting system generally uses a lighting source such as an incandescent lamp, an electric discharge lamp and a fluorescent lamp for a household, landscape and industrial usage. Here, a resistive lighting source including the incandescent lamp has a low efficiency and a heat generation problem. The electric discharge lamp has problems of a high price and a high voltage. The fluorescent lamp has an environmental disadvantage of mercury usage.
To overcome disadvantages of those lighting sources, there have been increasing interests in a light emitting diode (LED) having advantages of light-emitting efficiency, color variety and design autonomy. There have been increasing studies and researches on a lighting system including the LED as lighting source.
The LED is a semiconductor element which emits a light when a voltage is applied thereto forwardly. The LED has a long usage life, low power consumption, with electrical, optical and physical properties which are proper to mass production and the LED has been rapidly replacing the incandescent lamps and fluorescent lamps.
Generally, a lighting apparatus uses commercial Alternative Current (AC) power lines as electricity supply source. As a result, a lighting apparatus having the LED as lighting source has to be operated by the commercial AC power lines, too.
A conventional lighting apparatus having the conventional incandescent lamp as lighting source controls luminosity of the incandescent lamp, namely, dimming by using a dimmer. A phase control dimmer using a triode AC switch (e.g., TRIAC) is generally used as the dimmer. The phase control dimmer uses the TRIAC to be controlled and switched on at a predetermined phase angle of a voltage waveform of the commercial AC power and it converts the on-phase angle to control dimming freely.
Relating to that, the phase control dimmer is used to control the dimming of the LED lighting apparatus. Here, the LED lighting apparatus generally rectifies the input commercial AC power and controls a smoothing capacitor with a high capacity to suppress variation of the power voltage after that. As a result, even when the phase control dimmer lowers the input commercial AC power to control dimming, the smoothing capacitor stores sufficient electric charge for the LED to be luminous and it controls currents of the LED to be uniform. Because of that, the dimming required by the phase control dimmer is not controlled. In other words, the dimming of the LED is not lowered in the LED lighting apparatus as much as the dimming controlled by the phase control modulator, compared with the incandescent lamp lighting apparatus.